Industries which utilize automated production techniques, such as the assembly line production method employed by the automobile industry, utilize numerous transfer systems for transferring articles or workpieces between adjacent production machines or between adjacent working stations on a single machine. These transfer systems have conventionally been mounted directly on the production machine and normally employ oscillating or reciprocating shuttle for moving the workpieces. Many different types of transfer systems have been utilized for this purpose, such as mechanical, electro-mechanical and hydraulic-mechanical units. All of these known transfer systems have, to the best of our knowledge, possessed a common disadvantage in that the transfer system, due to the fact that it must be provided with its own power or driving unit, has thus been substantially large and bulky. Since the space which is available around or on a production machine, such as a multiple-spindle drilling machine, is severely limited, the known transfer systems have thus greatly restricted the desired utilization of this available space. Further, in some instances, the size of the known transfer systems has prevented their utilization in many situations where use of same is desired or, in the alternative, has required that a smaller and less desirable transfer system be utilized which does not result in the optimum or most efficient handling and transferring of the workpieces.
In evaluating a transfer system for use in conjunction with a production machine, it has generally been concluded that the transfer system must necessarily be mounted directly on or adjacent the production machine, and this thus severely restricts the size of the usable transfer system in view of the limited available space. At the same time, the transfer system must be capable of permitting efficient and repetitive transfer of articles or workpieces between adjacent stations, with the required time for accomplishing each transfer cycle or operation being extremely small, such as in the order of several seconds. Still further, it is desired that the transfer operation be controlled so as to minimize the jerking or impact forces which are imposed not only on the transfer system, but also on the workpieces. That is, the workpieces must be picked up from a stationary position and accelerated to a high speed and then immediately decelerated and brought to a stationary condition at a new location, which movement of the workpiece must take place in an extremely short period of time and yet displace the workpiece over a substantial distance which may be in the order of several feet, without imposing severe jerks or acceleration forces on either the workpiece or the transfer system. In addition to the above, the transfer system should be of minimum cost and must be possessed of substantial durability and reliability since these systems are utilized repetitively for long periods of time and are often exposed to substantial abuse during conventional assembly line production techniques. While numerous transfer systems are presently available and are being commercially utilized, nevertheless most of these systems fail to meet the criteria previously mentioned, and thus possess features or characteristics which are less than optimum.
Accordingly, it is an object of the present invention to provide an improved transfer system which overcomes many of the disadvantages associated with the known systems, and which more closely meets the desired criteria for systems of this type as explained above. More specifically, it is an object of this invention to provide:
1. A transfer system, as aforesaid, which employs a transfer mechanism positioned on or directly adjacent the production machine, the transfer mechanism utilizing a conventional hydraulic driving device such as a pressure cylinder, and which also employs a hydraulic drive unit located remotely from the production machine and the transfer mechanism mounted thereon, whereby only the transfer mechanism needs to be located in the direct vicinity of the production machine permitting the size of this transfer mechanism to be substantially minimized so that valuable space adjacent to or on the production machine is not taken up or interfered with by the transfer system.
2. A system, as aforesaid, wherein the remote hydraulic driving unit employs a mechanical mechanism for driving a pumping cylinder, the latter in turn being connected through conduits with the hydraulic drive of the transfer mechanism, whereby the mechanical drive can be utilized to provide the desired motion pattern to the pumping cylinder, which in turn transmits this desired motion pattern to the hydraulic drive of the transfer mechanism.
3. A system, as aforesaid, wherein the mechanical drive comprises a cycloidal drive which permits the acceleration and deceleration of the pumping cylinder and of the transfer mechanism to gradually increase from or decrease toward zero during the respective starting and stopping of the workpiece during performance of a transfer operation, thereby avoiding the imposition of jerking and large acceleration forces on both the workpiece and the transfer system. This cycloidal mechanical drive also provides a controlled motion pattern for the workpiece which, in addition to avoiding sudden and abrupt changes in acceleration, particularly on starting and stopping, also provides a motion pattern which enables the transfer operation to be carried out during an extremely small time interval so as to enable the utilization of a high and efficient production rate.
4. A system, as aforesaid, which utilizes a hydraulic cylinder for driving the cycloidal mechanical drive, which cylinder itself results in zero acceleration at the instant of startup and stopping, with the acceleration rapidly increasing and decreasing during the respective starting and stopping of the cylinder, with the movement of the cylinder being of a fairly constant velocity over a major portion of the stroke thereof, whereby this velocity and acceleration pattern when superimposed with those of the cycloidal mechanical drive accordingly result in a very desirable motion pattern for the transfer mechanism while avoiding the imposition of substantially instantaneously large velocities and accelerations at the instant of starting or stopping.
5. A system, as aforesaid, wherein the pumping cylinder associated with the remote hydraulic driving unit employs an elongated stationary piston rod having an intermediate piston fixed thereto and surrounded by an axially slidable cylinder housing, which cylinder housing is in turn drivingly controlled by the cycloidal mechanical drive, which latter drive employs a slide unit slidably guided on a pair of spaced stationary guide rails one of which has a stationary gear rack associated therewith, which slide additionally partially slidably supports and guidably controls the slidable movement of the pumping cylinder housing.
6. A system, as aforesaid, wherein the pumping cylinder, the cycloidal mechanical drive and the driving cylinder are all disposed in adjacent side-by-side relationship so as to form a unitized assembly of minimum size which can be suitably positioned at any desired remote location and interconnected to the hydraulic driving unit associated with the transfer mechanism, as by means of underground or overhead conduits.
7. A system, as aforesaid, which is of minimum structural and operational complexity, which can be manufactured efficiently and economically, which is durable and dependable in operation, and which results in a highly desirable motion pattern for permitting optimum and efficient repetitive transfer of articles at a high rate.
Other objects and purposes of the invention will be apparent to persons familiar with systems of this general type upon reading the following specification and inspecting the accompanying drawings.